The present invention relates generally to the field of semiconductor fabrication, and more particularly, relates to systems and methods that facilitate control and fabrication of nitrogen containing dielectric layers.
Semiconductor devices continue to be reduced in dimensions while maintaining or increasing in performance in response to an ever-increasing demand. This increasing demand is likely to continue and requires improvements in semiconductor fabrication processes and structures. Improvements in semiconductor processes permit fabrication of semiconductor devices in smaller dimensions and in higher density, quantity, and reliability. Improvements in semiconductor structures typically yield greater circuit performance, power control, and reliability.
Semiconductor devices are comprised of a number of materials, components, structures, and layers. One type of layer employed in semiconductor devices is a dielectric layer, which is comprised of dielectric material. Dielectric materials, also referred to as dielectrics, exhibit a large attractive force between the nucleus and orbiting electrons and have a net effect of a large amount of resistance to the movement of electrons. Dielectrics have low conductivity and high resistivity in contrast to conductive materials that have a high conductivity and low resistivity. Additionally, dielectrics can be divided into low-k dielectrics, which have a relatively low capacitance and resistance (but still higher than that of a conductive material), and high-k dielectrics, which have a relatively high capacitance, resistance and low conductance. The xe2x80x9ckxe2x80x9d refers to the dielectric constant of particular dielectric materials. Dielectrics, particularly high-k dielectrics, are often utilized in capacitor and capacitor like structures in semiconductor devices. Such structures are formed whenever a dielectric layer is formed between two conductors. For example, capacitor structures are formed in MOS gate structures by forming a dielectric layer between metal or polysilicon layers and silicon substrates.
As dielectric layers become thinner, leakage current and diffusion of materials (e.g., boron) become problematic. Nitridation of these dielectric layers can mitigate some of the problems. However, incorporation of nitrogen into dielectric layers, particularly high-k dielectrics that comprise dielectric compounds, can be difficult and can introduce additional problems.
The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention incorporates nitrogen into a dielectric compound as part of a deposition process without substantially harming an underlying semiconductor layer (e.g., silicon). The present invention incorporates nitrogen, controllably and/or uniformly, into a high-k dielectric layer. The incorporated nitrogen can reduce undesired crystallization, leakage current, diffusion and the like.
A dielectric layer in accordance with the present invention is a composite of a number of sub-layers, which are respectively formed via a two stage process. First, a sub-layer, comprised of a dielectric compound such as HfSiO, is formed via a suitable deposition technique (e.g., chemical vapor deposition) and secondly, the sub-layer is nitrided by a nitridation procedure. As a result, the sub-layer comprises nitrogen (e.g., HfSiON). The remaining sub-layers are similarly formed and collectively comprise the dielectric layer.
To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and implementations of the invention. These are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.